Follow-Up
Follow-Up is a Watcher common attack that deals 7 damage and refunds 1 energy if the previous card played was an attack. This conditional energy recovery means that in a sequence of attacks, Follow-Up essentially costs 0 energy when chained after another attack. The Watcher often wants to play multiple attacks in Wrath stance, and Follow-Up fits naturally into those attack chains, effectively becoming a free 7-damage card (doubled to 14 in Wrath).
Follow-Up rewards aggressive play patterns where you lead with one attack and immediately chain into Follow-Up for free. In Wrath, two attacks back-to-back (the first attack into Follow-Up) generate 14+14=28 total damage for 1 energy — exceptional efficiency. The condition is easy to fulfill since the Watcher has many cheap attacks. Multiple copies of Follow-Up can even chain together as long as you play an attack immediately before each. Upgraded, Follow-Up deals 10 damage instead of 7, improving the overall damage ceiling of the combo.